Thread inspection systems and methods

ABSTRACT

A screw thread measurement system and methods may comprise a frame having a reference surface, a carrier coupled to the frame and configured to translate relative to the frame, a dimension measurement system coupled to the carrier and having a thread contact element configured to translate relative to the frame and orthogonally the translation axis of the carrier. The dimension measurement system configured to determine thread dimensions relative to the frame reference surface.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a non-provisional of U.S. Provisional ApplicationSer. No. 62/196,110, filed on Jul. 23, 2015, and claims priority andbenefit thereto. The entire contents and disclosure of U.S. ProvisionalApplication Ser. No. 62/196,110 is incorporated herein for all purposes.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

REFERENCE TO APPENDIX

Not applicable.

BACKGROUND OF THE INVENTION Field of the Invention

The inventions disclosed and taught herein relate generally toinspecting and/or measuring the dimensions of screw thread systems; andmore specifically related to, but are not limited to, inspecting andmeasuring wedge thread systems.

Description of the Related Art

Screw thread systems, or simply threads, are used throughout industry toconnect or couple two or more items. For example and without limitation,threads are used on oilfield tubular products, such as casing, to jointogether two sections or joints and to provide a leak resistant, loadbearing connection. There exists in use today a wide variety of publicand proprietary thread forms. One type of thread form routinely used foroilfield tubulars is the “wedge” thread. For purposes of thisdisclosure, a wedge thread increases in root width in oppositedirections on a pin member and a box member. In other words, the axialdistance between the load flank of a wedge thread and stab flank of awedge thread (i.e., the thread width) increases in opposite directions.The increasing (and decreasing) width of a wedge thread is an artifactof the difference in thread lead for the stab flank and the load flank.This difference in lead causes the threads to vary in width along thescrew thread system.

For purposes of this disclosure, the term “load flank” refers to thesidewall surface of the thread that faces away from the pin end or boxend of the tubular. The load flank reacts the weight and other forces ofthe tubular members hanging in the well bore. The term “stab flank”designates the sidewall surface of the thread that faces toward the pinor box end and reacts forces tending to compress the tubulars towardeach other.

In practice, such as during manufacture, the width of the wedge threadat a single axial location, such as, for example, the middle (e.g.,6^(th)) thread is used as a proxy for the dimensional accuracy of theentire thread system. The industry has come to refer to this singlelocation as the “sweet spot;” that is, the mid-point of the threadlength where the groove width and tooth width are equal. Of course, eachthread system manufacturer can define the “sweet spot” however itchooses, or not at all. In other words, it is conventional for thedimensional accuracy of a wedge thread system to be judged based on thedimensions of the “sweet spot.” If the thread width at this knowlocation meets the tolerance for that location based on the designschematics, the entire wedge thread system is deemed acceptable. Thesewidth measurements are typically made using a conventional depth gage,such as the DG-1000 series available from Gagemaker, LP of Pasadena,Tex.

FIG. 1 depicts a prior art DG-1000 series depth gage in use to measurethe load and stab flanks of the sweet spot of the pin end of an oilfieldtubular 102. In practice, the depth gage 100 is referenced to the pinend 112, and the measurement head 108 is manually translated or extendeduntil the contact probe 110 contacts the desired thread root. Once thecontact probe is in the desired position (e.g., contacting the threadroot and thread flank) the distance from the reference surface 112 tothe thread flank can be read from the gage display 106. The measurementhead 108 can be manually translated across the thread root to theassociated flank and another measurement taken. The difference betweenthese two measurements establishes the thread width and the measureddistance from the pin end. These measurements are compared to the designdimensions to assess whether the thread system has been manufactured tospecifications.

If threads at other locations on the product 102 are desired to bemeasured, the operator/inspector typically must remove the gage 100 fromthe tubular product, relocate it to the desired position, and reset thegage against the reference point 112 (e.g., pin end) and repeat themeasurement process.

FIG. 2 illustrates another prior art system and method for determiningwhether a wedge thread system conforms to design specifications usingmeasurements at the sweet spot. A gage pin 208 comprises contactsurfaces 206 a and 206 b at one end. The outer surfaces of contacts 206a and 206 b are configured at a predetermined width “w” 202, such as,for example, the design width “w” at the sweet spot, e.g., a width of0.2841 inch (7.2161 mm) at a distance of 5.24215 inches (133.151 mm)from the datum. In use, the gage pin 208 is placed in a wedge threadroot wider than the width of the gage pin contact surfaces 206 a and 206b. The user manually slides the gage pin along the root surface in thedirection of narrowing thread root until the gage pin contact surfaces206 a and 206 b engage the stab flank 212 and load flank 210,respectively. Once the gage pin is firmly located in position in thethread system, a depth gage, such as the DG-1000 series discussed above,is used to measure the distance 204 from a reference or datum surface,such as a pin or box end, to the gage pin 208. This distance, correctedas desired to indicate stab flank distance or load flank distance orcenterline distance is compared against design specifications. It willbe appreciated that these gross inspections are incapable of determiningif the stab lead or the load lead is in error, and can only determinethat the thread width at that particular location does or does notconform to design specifications.

The present invention is directed to screw thread inspection systems andmethods useful for measuring wedge threads at a variety of locationsthat overcome many of the limitations of prior art systems and providesadditional measurement and inspection functionality.

BRIEF SUMMARY OF THE INVENTION

A non-limiting general summary of the inventions disclosed and taughtherein may be expressed as, the inventions disclosed and taught hereincan measure along the Z-axis every stab flank and load flank withreference to the datum face at positions between 0° through 360°; canacquire and/or store, internally or to a remote database, allmeasurements taken, via wired transmission or wireless transmission,such as, Bluetooth, Radio Frequency or Wi-Fi; can calculate the grooveor root width based off of the stab flank measured length from thedesign Sweet Spot; can calculate the groove or root width based off ofthe load flank measured length from the design Sweet Spot; can create adisplay or report, such as a sinusoidal mathematical curve, of thegroove or root width based off of the stab flank measured length fromthe design Sweet Spot and/or the groove or root width based off of theload flank measured length from the design Sweet Spot; can display orreport the errors/variance to design parameters of each groove widthlocation from the datum face up the taper cone of a thread system; cancalculate the length and radial circumferential location from the designSweet Spot to the measured location; can provide a best average of anygroove width and location that is out of design tolerance, which groovewidth is smaller than design parameters; can display or report, such asby plotting make-up length loss based on grooves or roots that arenarrower than design widths; can measures the lead parallel to theZ-axis axis; and/or can display or report, such as by plotting, all staband load flanks relative to the datum for “Drunken” lead of each flank;and can store all measured values to one or more files, includingoperators name, part serial number, job order number, date, pipe heatnumbers and traceability certifications.

Another non-limiting summary of the inventions disclosed and taughtherein may be expressed as a screw thread inspection system may comprisea frame having a first portion configured as a datum reference surfacedefining a plane and a second portion; a dimension measurement systemcoupled to the second frame portion and configured to determine distancefrom the datum reference surface along a first axis perpendicular to thereference surface plane; the dimension measurement system alsoconfigured to translate along a second axis perpendicular to the firstaxis; and a data processing system configured to receive and manipulatedistance data received by the dimension measurement system. Thedimension measurement system may be configured to determine distancefrom the frame along the second axis. The dimension measurement systemmay be coupled to a trolley configured to translate along the secondaxis relative to the second frame portion. The dimension measurementsystem may comprise a slider, a measurement head at one end of theslider and a thread contact probe associated with the measurement head.The dimension measurement system may comprise a support structureconfigured to augment the structural rigidity of the dimensionmeasurement system. The data processing system may be housed with oradjacent the dimension measurement system. The data processing systemmay be remote from the dimension measurement system. The dimensionmeasurement system may comprise wired or wireless data transmissioncapability to the remote data processing system. The remote dataprocessing system may be one or more of a smart phone, a tablet, aniPad, a laptop computer, a computer, a website, or any combinationthereof.

Yet another non-limiting summary of the inventions disclosed and taughtherein may be expressed as A method of inspecting a screw thread systemwith any of the inspections systems described herein, the methodcomprising contacting the datum reference surface to a dimensionalreference associated with the thread system; zeroing the dimensionmeasurement system along the first axis to the dimensional reference;translating a contact element associated with the dimension measurementsystem along the first axis to a first thread system artifact; acquiringdata representing the distance along the first axis from the dimensionalreference to the first artifact; translating the contact element alongthe first axis to a second thread system artifact; acquiring datarepresenting the distance along the first axis from the dimensionalreference to the second artifact; and determining the distance betweenthe first and second artifact. This method can be applied to a wedgethread system having a plurality of stab flanks and a plurality of loadflanks. The first thread system artifact may be a stab flank and thesecond artifact may be a load flank. The first and second artifacts areassociated with a predetermined thread design sweet spot having a designdistance from the dimensional reference. The methods may also comprisecomparing at least one of the stab flank distances or the load flankdistances with the predetermined sweet spot design distance. The methodsmay also comprise creating a report of the variance between at least oneof the stab flank distances or the load flank distances and the designdistance for the predetermined sweet spot. The methods may also compriseacquiring a plurality of additional stab flank distances along the firstaxis for the thread system and determining a stab flank lead for thethread system. The methods may also comprise acquiring a plurality ofadditional load flank distances along the first axis for the threadsystem and determining a load flank lead for the thread system. Themethods may also comprise acquiring a plurality of additional stab flankdistances along the first axis for the thread system; calculating a stabflank lead for the thread system; acquiring a plurality of additionalload flank distances along the first axis for the thread system;calculating a load flank lead for the thread system; comparing at leastone of the calculated stab lead and load lead against a correspondingdesign lead; and reporting a variance between the at least one of thecalculated stab lead and load lead and the corresponding design lead.The methods may also comprise determining whether the thread systemsuffers one or more drunken leads. The methods may also comprisegenerating a report from the measured data, which includes at least oneof: an operator's name, a part serial number, a job order number, adate, a pipe heat number or a traceability certification.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The following figures form part of the present specification and areincluded to further demonstrate certain aspects of the presentinvention. The invention may be better understood by reference to one ormore of these figures in combination with the detailed description ofspecific embodiments presented herein.

FIG. 1 illustrates a prior art wedge thread inspection system utilizinga conventional depth gage.

FIG. 2 illustrates a prior art wedge thread inspection system comprisinga gage pin.

FIG. 3 illustrates one of many possible embodiments of a digitalinspection system according to the present inventions configured tomeasure or inspect external thread systems.

FIG. 4 illustrates one of many possible embodiments of a digitalinspection system according to the present inventions configured tomeasure or inspect internal thread systems.

FIG. 5 illustrates the external inspection system of FIG. 3.

FIG. 6 illustrates the internal inspection system of FIG. 4.

FIGS. 7A and 7B illustrate an embodiment of a contact probe useful withwedge thread systems.

FIG. 8 illustrates the contact probe of FIGS. 7A and 7B in a wedgethread system.

FIG. 9 illustrates an alternate embodiment of a thread inspection systemaccording to the present invention.

FIGS. 10A and 10B illustrate a typical wedge thread with various threadparameters identified.

FIG. 11 illustrates the type of data that may be inputted to a dataprocessing system and the type of calculations that may be carried outby a data processing system according to the present inventions.

FIGS. 12A-12D illustrate other various wedge thread parameters useful ininspecting thread systems according to the present inventions.

FIG. 13 illustrates the type of data that may be inputted to a dataprocessing system and the type of calculations that may be carried outby a data processing system.

While the inventions disclosed herein are susceptible to variousmodifications and alternative forms, only a few specific embodimentshave been shown by way of example in the drawings and are described indetail below. The figures and detailed descriptions of these specificembodiments are not intended to limit the breadth or scope of theinventive concepts or the appended claims in any manner. Rather, thefigures and detailed written descriptions are provided to illustrate theinventive concepts to a person of ordinary skill in the art and toenable such person to make and use the inventive concepts.

DETAILED DESCRIPTION

The Figures described above and the written description of specificstructures and functions below are provided to teach any person skilledin the art how to make and use the inventions for which patentprotection is sought. The figures and description of possibleembodiments are not presented to limit the scope of what has beeninvented or the scope of the appended claims. Rather, this disclosure isprovided so that once it has been studied, a person of skill in the artwill be able to practice the inventions in an unlimited number ofembodiments, subject to Applicant's rights bestowed by the Constitutionand other laws of the United States. Those skilled in the art willappreciate that, for the sake of clarity and understanding, not allfeatures of a commercial embodiment of the inventions are described orshown. Persons of skill in this art will also appreciate that thedevelopment of an actual commercial embodiment incorporating aspects ofthe present inventions will require numerous implementation-specificdecisions to achieve the developer's ultimate goal for the commercialembodiment. Such implementation-specific decisions may include, andlikely are not limited to, compliance with system-related,business-related, government-related and other constraints, which mayvary by specific implementation, location and from time to time. While adeveloper's efforts might be complex and time-consuming in an absolutesense, such efforts would be, nevertheless, a routine undertaking forthose of skill in this art having benefit of this disclosure. It must beunderstood that the inventions disclosed and taught herein aresusceptible to numerous and various modifications and alternative forms.Lastly, the use of a singular term, such as, but not limited to, “a,” isnot intended as limiting of the number of items. Also, the use ofrelational terms, such as, but not limited to, “top,” “bottom,” “left,”“right,” “upper,” “lower,” “down,” “up,” “side,” “X,” “Y,” “Z” and thelike are used in the written description for clarity in specificreference to the Figures and are not intended to limit the scope of theinvention or the appended claims.

Particular embodiments of the invention may be described below withreference to block diagrams and/or operational illustrations of methods.It will be understood that each block of the block diagrams and/oroperational illustrations, and combinations of blocks in the blockdiagrams and/or operational illustrations, can be implemented by analogand/or digital hardware, and/or computer program instructions. Suchcomputer program instructions may be provided to a processor of ageneral-purpose computer, special purpose computer, ASIC, and/or otherprogrammable data processing system. The executed instructions maycreate structures and functions for implementing the actions specifiedin the block diagrams and/or operational illustrations. In somealternate implementations, the functions/actions/structures noted in thefigures may occur out of the order noted in the block diagrams and/oroperational illustrations. For example, two operations shown asoccurring in succession, in fact, may be executed substantiallyconcurrently or the operations may be executed in the reverse order,depending upon the functionality/acts/structure involved.

We have created screw thread inspection systems and methods useful formeasuring the dimensions of screw thread systems, such as, but notlimited to, wedge thread systems. In general, our inventions comprise aframe system that is configured to provide several functions. The framemay be structured to have two portions: a reference or datum surface orsurfaces configured to engage or contact a portion or multiple portionsof the part on which the screw thread system resides, and a carrierportion. The carrier portion may be “universalized” so that it can becoupled with multiple different datum surfaces for use with multipledifferent thread systems or threaded products. For example, and withoutlimitation, a datum surface may comprise removable or replaceablebumpers. Such bumpers can be made from a wide variety of suitablematerials, including, but not limited to, metal, Teflon, High DensityPolyethylene, and other such materials. In practice, the datum orreference surface(s) should engage or contact a reference or datumsurface on the part, such as the pin end of a threaded tubular product.A goal of the reference surface configuration is to provide a repeatableand accurate reference surface for multiple thread measurements, withoutmarring or damaging the part.

The frame may be structured to have a portion, such as the carrierportion, configured to support an analog or digital dimensionmeasurement system, such as, without limitation, a dial indicator gage,a linear indicator gage, or a digital measurement gage. In most, but notnecessarily all, embodiments, the measurement axis of the dimensionmeasurement system will be orthogonal or normal to the plane of thereference or datum surface(s). The carrier portion of the frame may beconfigured to allow the dimension measurement system to move relative tothe reference surface and preferably orthogonally to the measurementaxis. For example, the dimension measurement system may be coupled tothe carrier such that the dimension measurement system (or at least aportion thereof) may translate relative to the frame along themeasurement axis (e.g., Z-axis), and translate relative to the frame andorthogonally to the measurement axis (e.g., X-axis). Typically, theZ-axis is also the centerline of the thread system, and the X-axisintersects the Z-axis orthogonally. A trolley or other structure can beprovided on the carrier to support translation in the X-axis. Thecarrier portion also preferably comprises a dimension measurementsupport system configured to provide additional rigidity and support tothe measurement system slide in all planes to resist bending andunwanted movement.

Embodiments may or may not comprise one or more cosmetic coversassociated with inspection system. If provided, such covers may providea grip or gripping surfaces for handled operation; may provide dirt ordebris protection to the moving and/or sensitive components of thedimension measurement system and trolley; house one or more powersources, such as batteries; and/or house wired and/or wirelesscommunications functionality.

The dimension measurement system comprises a Z-axis displacementtransducer, such as but not limited to a resistive sensor; a capacitivesensor; an inductive sensor, such as an LVDT, an LVRT and/or an LVIT; amagnetic sensor, such as a Hall-Effect sensor; a time-of-flight sensor,such as an MLDT, ultrasonic, or laser sensor; or a pulse encodingsensor. Any of these may be configured to detect and determine relativeor absolute displacement in the axial or Z-axis direction. Additionallyor optionally, the carrier may comprise one or more transducers, such asbut not limited to a resistive sensor; a capacitive sensor; an inductivesensor, such as an LVDT, an LVRT and/or an LVIT; a magnetic sensor, suchas a Hall-Effect sensor; a time-of-flight sensor, such as an MLDT,ultrasonic, or laser sensor; or a pulse encoding sensor. Any of thesemay be configured to detect and determine relative or absolutedisplacement in the radial or X-axis direction.

In some embodiments, the frame, and particularly the datum surface, maycomprise one or more openings or windows through which the dimensionmeasurement system may translate along the Z and X axes. Also, the framemay be configured to minimize the weight of the inspection system tosupport handheld operation.

Referring back to the reference or datum surface and bumpers describedabove, the reference surface may be an axial reference surface in thatthe reference surface (i.e., a segment normal to the reference surface)is collinear with the longitudinal measurement axis (Z-axis). For athreaded product, such as a tubular product, a radial reference point orsurface(s) may also be provided that is configured to reference againstan outer or inner radial surface of the part. Axial (Z-axis), radial(X-axis) and other reference surfaces or points may be provided asneeded or desired.

The dimension measurement system may comprise a portion, such as ameasurement head, to which a thread contact or probe element may besecured. The thread contact element is preferably configured for usewith the particular screw thread system to be measured. For example, thethread probe element may be a substantially spherical body of known orpredetermined dimension or any other shape of known dimensions. Thus, inpractice, when the thread contact element engages the screw thread, thepredetermined dimensions of the contact element will inform the user ofthe inspection system precisely where the contact element engages thescrew thread (such as the specific location on a load flank). With thistype of information, a determination of whether the screw thread iswithin or without tolerance at that specific location can be determined.Alternately or additionally, the measurement head may support two ormore thread contact or probe elements to make a planar measurement,rather than a point measurement. The dimension measurement system may beconfigured to indicate absolute measurements (i.e., relative to thereference surface(s)) or relative measurements (e.g., relative to thescrew thread system under inspection).

The inspection systems described herein may provide relative or absolutemeasurements. For example and not limitation, an absolute measurement inthe Z-axis requires that the dimension measurement system be “zeroed”against a known reference point, such as the pin end. To facilitatezeroing or datuming the dimension measurement system, a gap or slot maybe required in or between datum bumpers so that the measurement headcontact probe can be retracted along the Z-axis to the pin end and thentranslated along the X-axis so that the contact probe contacts the pinend or other absolute reference point. Once in position, the dimensionmeasurement system may be zeroed or referenced to this point in knownmanner, such as by activating a zeroing functionality. To the extent thedimension measurement system needs to be zeroed in the X-axis a similarprocedure may be employed, including zeroing against the root of thefirst full thread.

For embodiments of the inspection system utilizing electronic dimensionmeasurement systems, the measurement system may comprise one or moretactile buttons or a touch screen providing power (on/off), measurement,units, recording, and/or transmission functionalities. For example andnot limitation, the dimension measurement system may comprise a “record”feature, which when activated will acquire and/or store and transmit thethen existing dimensional information (e.g., absolute or relativemeasurement). Alternately or additionally, the inspection system maycomprise “record load flank” and “record stab flank” functionality aswell as “clear last,” clear all” and “transmit” functionality.Alternately or additionally, recording of measurement can be time basedsuch that if a single measurement value is sampled over a definedperiod, the system may assume a measurement is intended and the valuemay then be recorded. A visual or auditory signal, such as a beep, maybe provided to indicate that a measurement has been recorded ortransmitted. In a preferred electronic embodiment, a digital dimensionmeasurement system comprises “start” functionality, “record”functionality and at least two differently colored indicators.

These measurements may be reported or indicated optically, such as by adial indicator, scaled rule or digital display, and/or may be stored ortransmitted electronically in analog or digital format. For example, andwithout limitation, the inspection system, and preferably the dimensionmeasurement system can record or store measurements to persistent orremovable memory, such as a removable SD card. Alternately oradditionally, the inspection system, and preferably the dimensionmeasurement system can transmit measurement data and/or otherinformation electronically, either through wired or wireless protocols.In a preferred embodiment, the inspection system transmits and receivesdata via Bluetooth® or another IEEE 802.15 wireless transmission to adata storage and processing system. Regardless of data transmissionmethod, the data storage and processing system may comprise a smartphone, tablet (such as an iPad®), laptop computer, desktop computer,website, or cloud-based system. The data storage and processing systemmay be configured with processor(s), memory, software, and othercircuitry and components to compare the recorded measured data withtolerance data for the particular screw thread under inspection andprovide a report of whether the screw thread is within or without thescrew thread tolerances. For purposes of this disclosure, the phrase“inspection system” includes a data processing system whether residenton the handheld device or housed separately.

In a typical, but not exclusive operation, and using the pin end of anoilfield tubular as an exemplar, the operator powers on the digitaldimension measurement system, which provides a visual indication, suchas an amber light, that the inspection system is ready for use. Theoperator places the axial reference surface against the pin end of thetubular and the radial reference pins against an upper, outer surface ofthe pin end. The inspection system frame, e.g., the axial referencesurface, may comprise a detection system, such as a micro switch, thatis activated when the axial reference surface is operatively engagedwith the product's reference surface (e.g., pin end). Once the detectionsystem is activated by proper engagement of the inspection system withthe product, the visual indicator turns green, for example, indicatingthat the inspection system is ready to record measurements.Additionally, an indicator may be activated indicating the inspectionsystem is ready to record a stab flank measurement. The measurement headis translated axially (Z-axis) to the reference or datum point on thepin end, and the Z-axis measurement is zeroed to this point. The X-axisis also zeroed, either to this same reference point to another referencepoint, such as the root adjacent the stab flank of the first fullthread. Thereafter, the measurement head can be translated to anyportion of the screw thread of interest (e.g., the middle thread fromthe pin end) and the measurement head lowered into the thread (X-axis),such as by translating the carrier in a downward direction (or allowingthe biasing force to translate the measurement head), to cause thecontact element to touch the root of the screw thread.

The measurement head is translated so the contact element contacts boththe root surface and the stab flank surface, and is held in position.Assuming the inspection system indicator still shows green indicatingproper reference surface engagement (if provided), the stab flankmeasurement may be recorded by activating a record functionality. Oncethe data representing the stab flank measurement has been recorded, anindicator changes or activates to show that the inspection measurementsystem is ready to record a load flank measurement. The measurement headis translated in the axial direction (and radial direction, if needed)so that the contact element engages the root and load flank of the screwthread. Once the contact element is in position, and the indicator showsgreen, the load flank measurement may be recorded by activating therecord functionality. If recordation of data was effective, theindicator reverts to a stab flank ready condition. In accordance with ameasurement protocol previously established, the operator can move themeasurement head to a different, yet predetermined portion of the screwthread through axial translation, rotation of the inspection systemrelative to the part, or a combination of both. For example, theinspection system first may be oriented at 0° (e.g., 12 o'clock) andmeasurements of the 3^(rd), 6^(th) and 9^(th) threads obtained. Theinspection system may then be rotated to the 90° position (e.g., 3o'clock) and measurements of the 3^(rd), 6^(th) and 9^(th) threadsobtained. Similar measurements at 180° and 270° may be obtained as well,as desired. It will be appreciated a benefit of radial or X-axistranslation is that the inspection system does not have to disengagefrom the product reference surface. This results in more accurate andrepeatable measurements.

The inspection systems are also capable of measuring thread taper, whichis a relative measurement within the thread system and does notnecessarily requiring zeroing the dimension measurement system to areference point. Thread lead or pitch may also be determined. For wedgethread systems, stab flank lead and load flank lead may be determined.The inspection systems described herein can detect and quantify what isreferred to in the art as “drunken lead.”

In preferred embodiments, the digital dimension measurement system haswireless transmission capability, such as, but not limited to,Bluetooth®. While measurements are being acquired or recorded, such asto one or more memory buffers, whether in the Z-axis direction, X-axisdirection or both, the wireless transmission functionality packages thedata and transmits it to the remote data storage and processing systemwhere the data is organized and compared against tolerance data for theproduct being inspected. A report may be generated showing thecomparison of recorded data to tolerance data.

Turning now to the several figures that illustrate possible embodimentsof systems and methods utilizing one or more of the inventions discussedabove, FIG. 3 illustrates a wedge thread inspection system 300 shownduring inspection of an external wedge thread product 302, such as anoilfield tubular pin end. FIG. 4 illustrates a wedge thread inspectionsystem 400 shown during inspection of an internal wedge thread product402, such as an oilfield tubular box end. These figures will bedescribed together.

The inspection systems 300 and 400 comprise a frame system 304, 404,which may comprise one or more assemblies or components. It ispreferred, but not required that the frame system 304, 404 comprise twocomponents. A first frame component may be a datum face 304 a, 404 a andthe second component may be a carrier frame 304 b, 404 b. The datum facecomponent 304 a, 404 a and the carrier frame component 304 b, 404 b arepreferably removably coupled to one another, such as by threadedfasteners 305, 405. The frame system 304, 404 is preferably configuredto be held by a human hand and supports a dimension measurement system306, 406 such-as a digital depth micrometer. The measurement system 306,406 comprises a measurement head 308, 408, having one or more threadcontact elements or probes 310, 410 connected to a slide 316, 416. Framesystem 304, 404, and particularly datum face component 304 a, 404 acomprises a face or surface 312, 412 configured to register against areference or datum point or surface on the wedge thread product 302,402, such as for example the pin end or the box end of a threadedtubular product.

The wedge thread inspection system 300, 400 can translate in an axialdirection—that is, the measurement head 308, 408 can extend axially(along the Z-axis) to reach multiple threads along the product 302, 402length. Also, the measurement system 306, 406, and therefore themeasurement head 308, 408 can translate in a radial or verticaldirection (along the X-axis) orthogonal to the axial measurementdirection to accommodate for an increasing or decreasing radialdimension of the product 302, 402, such as for example a tapered screwthread.

In use, the user (human) will reference the wedge thread inspectionsystem 300, 400 to the product to be measured, such as by engaging thereference surface 312, 412 with the pin end as shown in FIG. 3, or thedatum surface 412 with the box end as shown in FIG. 4. The user may thenselect any thread of interest, such as the 2^(nd) thread as shown inFIG. 3, or the 10^(th) thread as shown in FIG. 4 The wedge threadinspection system 300, 400 can then measure the width of the thread atthat location by contacting the contact element 310, 410 against thethread root and load flank and then moving the measurement head 308, 408so that the contact element 310, 410 touches the root and stab flank ofthe thread, or vice versa. The difference between these two measurementsdefines the width of the thread root at that location, as corrected bythe dimensions of the contact element and the thread contact point, asdesired.

Referring to FIG. 4, the thread system on threaded product 402 comprisesa plurality of threads roots and crests when viewed along a singlemeasurement axis as illustrated. For example, thread crest 418 isbounded by thread root 420 and thread root 422. Depending on the designcriteria and/or inspection criteria of the specific thread system, thewidth of a thread root, such as root 420 can be determined, or the widthof the thread crest 418 can be determined, or both, regardless ofwhether the thread system is an internal or external thread system.

Turning now to FIG. 5 and FIG. 6, preferred embodiments of a wedgethread inspection system 500, 600 are illustrated. Similar to previousinspection systems described, the inspection system 500, 600 comprises aframe system 502, 602 preferably constructed from a light material suchas aluminum or fiberglass or other composite type material. Frame system502, 602 preferably comprise two components, a datum face component 502a and 602 a, and a carrier component 502 b, 602 b. These two framesystem components are removably coupled together by fasteners, such asthreaded fasteners 505, 605. It will be appreciated that inspectionsystem 500 is configured to measure external threads, and inspectionsystem 600 is configured to measure internal threads. It will alsoappreciated that a single carrier component 502 b, 602 b can be mated toeither an external thread datum face component 502 a or an internalthread datum face component 602 a.

Weight reducing holes or voids may be strategically placed in the framesystem 502, 602, such as in datum face components 502 a, 602 a to reduceits weight without affecting its strength or rigidity. The datum facecomponent 502 a, 602 a has a reference surface, which preferablycomprises axial reference bumpers 506 a, 506 b and 506 c (606 a, 606 band 606 c). Preferably, the datum face component 502 a, 602 a comprisesthree axial reference or datum bumpers 506 a, 506 b and 506 c (606 a,606 b and 606 c) arranged generally triangularly, as shown. In addition,one or more radial reference points 508, 608 are also provided toreference off the external pin end or internal box end.

It is preferred, but certainly not required, that the reference bumper506 c, 606 c at the apex of the triangle comprises a micro switch 550,650 or other transducer configured to indicate, such as by generating asignal, that the reference bumper 506 c, 606 c is in operational contactwith the work piece reference surface.

Frame 502, 602 comprises a main window 510, 610 through which ameasurement head 512, 612 may pass. Measurement head 512, 612 comprisesa contact probe 514, 614 of known dimension for contacting the threadprofile to be measured. The measurement head 512, 612 is operativelyconnected to a slider 516, 616 that operatively interfaces with adimension measurement system 518, 618, for example a digital depthgauge, such as those available from Sylvac or Gagemaker LP. Themeasurement system 518, 618 and slider 516, 616 are attached or coupledto a trolley 520, 620 that is free to translate in the positive andnegative X directions, as shown. In this particular embodiment, thedimension measurement system assembly (512, 520 and 516) and (612, 620and 616) is biased in the negative X direction. This motion (e.g.,radial displacement) allows the measuring head 512, 612 to be raised orlowered relative to the workpiece (e.g., 102) being measured, such aswhen measuring tapered threads.

The dimension measurement system 518, 618 is preferably mounted to astiffening component 538, 638 that spans the length of the slider 516,616. The slider 516, 616 may slide relative to the stiffener 538, 638,or preferably, the slider 516, 616 is rigidly coupled to the stiffener538, 638 and the slider/stiffener assembly may translate as a unit. Itwill be appreciated that the stiffener 538, 638 provides additionalsupport and rigidity to convention digital depth gages, and prevents orreduces measurement errors caused by bending, torqueing or otherunwanted deflections in the dimension measurement system 518, 618.

Optionally, the embodiments illustrated in FIG. 5 or 6 may comprise adimension measurement system 518, 618 that can detect and transducedisplacement in the radial or X-axis direction. Alternately, the X-axisdisplacement measurement system may be separate from the axial (Z-axis)dimension measurement system 518, 618, and coupled to the carrier 502 b,602 b and/or trolley 520, 620, or some other structure allowingdifferential displacement measurement relative to frame 502, 602. As cannow be appreciated, the radial (X-axis) displacement between successiveflank measurements can be used to determine the taper or pitch line ofthe thread system.

It will be appreciated that to make absolute Z-axis measurements, thecontact probe 514, 614 should be zeroed against the datum surface of theproduct to measured or inspected. In the case of an oilfield tubular,the datum surface is the pin end or the box end. To facilitate zeroingthe inspection system 500, 600 against this datum surface, datum bumper506 c, 606 c may comprise a gap or slot 540, 640 configured to receivethe contact probe 514, 614 so that it can be referenced against the pinor box end. In this way, once the inspection system 500, 600 isreferenced to the tubular, the measurement head 512, 612 can betranslated toward the datum surface and then translated downward alongthe X-axis so that the contract probe 514, 614 contacts the datumsurface. The dimension measurement system 518, 618 can be zeroed toposition in the manner provided, such as by invoking a “zero” or“reference” functionality. It will be noted that not all measurementsneed to be zeroed to a datum. For example, and without limitation, ataper measurement does not require that the inspection system 500, 600be zeroed in either Z-axis or X-axis, however, such referencing to datumsurface is preferred. To reference the X-axis, typically the contactprobe 514, 614 will be zeroed against the root of the first thread andthe load flank.

The embodiments illustrated in FIGS. 5 and 6 comprise a wireless datatransceiver 530, 630 and a data port 532, 632 for wired datatransmission and reception, such as by Ethernet cable or USB cable, bothof which may be located on the dimension measurement system 518, 618 oradjacent the dimension measurement system. The dimension measurementsystem 518, 618 may comprise a display window 522, 622 and a pluralityof visual indicator and/or buttons 524, 624, 526, 626 with preprogrammedfunctionality. For example and not limitation, the inspection system500, 600 may comprise a taper functionality in which successivemeasurements are used to determine taper only; a width functionality inwhich successive measurements are used to determine thread width, or acombined functionality where all measurements include both Z-axis andX-axis measurements from which taper, width, lead and other threadsystem parameters may be determined.

FIGS. 7A and 7B illustrate a preferred form of thread contact or probeelement 700 that may be used with inspections systems described herein.Probe 700 may comprise a threaded portion or other engagement system 702configured for engagement with a measurement head (e.g., 512, 612). Forthreaded engagement, probe element 700 may also comprise a land,including a wrench land, 704. A contact element 706 is provided and isconfigured to interface with the screw thread system under measurementor inspection (as discussed with respect to FIG. 8). In this embodiment,the contact element has a curved sidewall having a constant radius,e.g., a radius of 0.02 inch. Sidewall(s) of varying or differentgeometries may be used as desired or required. The contact element 706is coupled, integrally or separately, with the engagement portion 702 bya shank 708. As is apparent from FIG. 8, it is preferred that shank havean outer surface with a diameter that is less than the outer diameter ofcontact element 706. This is especially beneficial for wedge threadsystems having a dovetail design, but is also beneficial for squaredesign wedge thread systems. Contact element 702 may have a distalsurface 710 that is flat or slightly convex in shape. For example, it ispreferred that surface 710 be spherically convex with a radius of about0.75 inch.

FIG. 8 illustrates probe 700 in a thread root 804 of thread system 802.Probe 700 is shown in measurement contact with the stab flank 806 andthread root 804. Based on the known, such as predetermined, dimensionsof the contact element 706, the contact point 810 between the contactelement 706 with thread flank 806 is known through calculation. Forexample, as illustrated the root floor is x′ away from the contactpoint, and the center of the probe 700 is located z′ away from thecontact point. This information can be used to generate reports or otherinformation about the dimensions of the thread system at the point ofmeasurement.

FIG. 9 illustrates yet another embodiment of an inspection system 900 inwhich the frame 902 comprises two portions (integral or separate) 902 aand 902 b. Frame portion 902 a may be similar to frame portions 502 aand 602 a described previously. Frame portion 902 b preferably lies inthe X-axis plane. Frame portion 902 b comprises two or more guide rails904 and 906 along which trolley 918 is configured to ride (i.e., slide)in the X-axis. The trolley may comprise, and preferably does compriseone more X-axis transducers 960, as described above, configured totransduce X-axis displacement as the trolley moves along guide rails904, 906. Alternately, frame portion 902 b may house the X-axistransducer.

Trolley 918, comprises a Z-axis displacement transducer 920 coupledthereto, such as described previously, to transduce axial (Z-axis)displacements. The Z-axis displacement transducer 920 also comprises aslider 922 and a stiffener system 924 to which the slider 922 is rigidlycoupled. The stiffener systems 924 may comprise one or more rails thatpass through the trolley 918 such as on bearings.

Having described systems and devices utilizing aspects of the inventionsdisclosed herein, we will now describe how these systems and devices maybe used. FIG. 10A illustrates a wedge thread system on the pin end of anoilfield tubular product 1002. As designed, this thread system has adesignated ‘sweet spot” 1004 on a particular stab flank located adistance “M” 1006 away from the reference datum (i.e., pin end). FIG.10A also illustrates a stab flank measurement 1008 and a load flankmeasurement 1010 at a location other than the sweet spot 1004. Alsoshown is pitch or taper line 1012 and the pitch diameter 1014, such asat the sweet spot 1004.

FIG. 10B is a close-up illustration of the thread system profile in FIG.10A. This figure establishes the various thread system parameters suchas the sweet spot 1004, the groove width at the sweet spot 1016, theload flank lead 1018, the stab flank lead 1020, the stab flank height1022, the load flank height 1024, the radial (X-axis) height from rootto sweet spot 1026, the stab flank angle 1028 and the load flank angle1030. It will be appreciated that in FIG. 10, the stab and load angles1028, 1030 are measured relative to the X-axis. As shown, those of skillin the art will now understand that the inspection system contact probes(e.g., 700) can be sized to directly contact the designed sweet spot1004 for a given thread system, or the actual contact point can becalculated and measurements converted to the designed sweet spot 1004.

FIG. 11 represents typical data that may be entered into a dataprocessing system configured for use with the inspection systems asdescribed above, such as data processing system 580, 680. In thisembodiment, all of the values 1102 through 1122 are inputted, such as bykeyboard, digital scanning, RFID, barcode or other electronic downloadfrom a physical or electronic file or data stream containing thesethread system design parameters. In this example, at least one of theinspection systems described above is used to obtain the measurement GS(1124) from the product under inspection. GS represents the distancealong the Z-axis from the datum (e.g., pin end) to the stab flank of thethread being measured (i.e., not necessarily the stab flank associatedwith the sweet spot). Based on this measured value and the inputteddesign parameters of the thread system, the data processing system willcalculate PL (1168), which is the distance along the Z-axis from thedatum to the load flank of the thread being measured. In this example,for a measured stab flank distance (GS) of 4.143 inches (105.2 mm), thedata processing system calculates that the load flank distance should be(PL) 3.87141 inches (98.3338 mm) along the Z-axis. The data processingsystem can compare the calculated value (3.87141 inches, 98.3338 mm) tothe measured value (e.g., 3.8753 inches (98.433 mm), not shown in FIG.11) revealing a variance or error of −0.00039 inch (−0.00988 mm) It willbe appreciated that the above example calculates the corresponding loadflank distance from a measured stab flank distance. It will beunderstood that the corresponding stab flank distance also can becalculated from a measured load flank distance.

Thus, the data processing system, whether as a separate system or aspart of an inspection system, may be programmed or otherwise configuredto run two calculations per thread groove to determine which of the loadflank lead or the stab flank lead conform to design specifications.Detected errors can be used to correct errors in the manufacturingprocess, such as CNC programming errors or implementation errors, suchas latency or hysteresis. First, stab flank distance from the referencedatum (e.g. pin end) is measured and stored on the dimension measurementsystem or transmitted to the data processing system (e.g., smart phone).Next, the load flank distance from reference datum is measured andstored and/or transmitted. The stab flank measurement (or calculatedmeasurement) is used as the design measurement at that point, and thecorresponding design groove or root width is determined, such as from alook-up table. The design location of the load flank length is thereforeknown by subtracting the root width to the stab length measurement andis compared to the load flank measurement (or calculated measurement).Any error between the design distance for the load flank and themeasured distance for the load flank may be reported.

For the same stab and load flank measurements, the load flank distanceis used as the design measurement at that point, and the correspondingdesign groove or root width is determined, such as from a look-up table.The design location of the stab flank length is therefore known (e.g.,calculated) and is compared to the stab flank measurement (or calculatedmeasurement). Any error between the design distance for the stab flankand the measured distance for the stab flank may be reported.

Because a wedge thread has a stab flank pitch or helical cycle and adifferent load flank pitch or helical cycle, by comparing the results ofthe calculations presented, a graphical representation can be generatedto display or show the pattern the manufacturing process is producing asit moves the threading tool up the taper cone. Thus, one advantage ofthe present invention is that it can document whether the manufacturingprocess produces the correct helical movement (i.e, flank pitch and leadmovement). The inventions may also show if the manufacturing process isnot able to correct itself fast enough to maintain the designparameters. The inventions described herein can determine if aparticular groove/root width is at the design distance from thereference or datum surface.

FIGS. 12A-12D illustrate in graphical detail the various geometric andtrigonometric relationships between the inputted and calculatedvariables presented above in FIGS. 10 and 11 in the circumstance whenthe load flank PL is the calculated value. Those of skill in the arthaving the benefit of this disclosure will be able to derive theequations necessary to calculate the stab flank PS from a measured loadflank value GL. As can be seen from FIG. 12D, the load flank distancefrom the datum is calculated asPL=M+ZPL+QL+Dwhere the variables are vectors and therefore may have negative value.Using the values from FIG. 11, the PL is calculated asPL=(5.24215 in.)+(−1.44297 in.)+(0.00023 in.)+(0.072 in.)=3.87141 inchesorPL=(133.151 mm)+(−36.6514 mm)+(0.00584 mm)+(1.829 mm)=98.3344 mm

FIG. 13 illustrates a tapered thread system, such as, but not limitedto, a wedge thread system. The Z-axis 1302 is shown perpendicular to thedatum surfaces 1304. Because the thread system forms a helix about thetaper cone, a helix axis 1306 is shown offset an angular amount from theZ-axis 1302. It will be understood by now that the inspection systemsdescribed above take measurements along the Z-axis 1302 as opposed tothe helix axis 1306. FIG. 13 demonstrates the offset between thread leador pitch (e.g., stab flank lead or load flank lead) as measured on theZ-axis and the helix axis. The systems described herein can convertZ-axis lead measurements to helix axis lead measurements as desired orrequired.

Further, the inspection systems methods disclosed herein can measure ordetermine what is colloquially referred to as “drunken lead.” Forexample, once an inspection system is reference to the product, such asa pin end comprising a wedge thread, the stab flank location of thefirst thread can be measured as well as the stab flank locations of eachsuccessive stab flank. The data processing system can calculate theaverage or composite stab lead and compare it to the design stab lead LS(1102 in FIG. 11). Of course, if the design stab lead is given relativeto the helix axis, rather than the Z-axis, the data processing systemcan convert the calculated Z-axis lead to a helix axis lead. It will beappreciated that the same inspection can be performed on the load flanklead.

It is intended and expressly disclosed that each of the features,functionalities and components described above with respect to FIGS.3-13 may be mixed, matched and combined in any order or configuration toproduce embodiments of inspection and data processing systems notexpressly described herein in words or figures.

Those persons of skill in the art having benefit of this disclosure willnow appreciate that the inspection systems describe herein, comprisingdata processing systems described herein, can measure along the Z-axisevery stab flank and load flank with reference to the datum face atpositions between 0° through 360°; can acquire and/or store, internallyor to a remote database, all measurements taken, via wired transmissionor wireless transmission, such as, Bluetooth, Radio Frequency or Wi-Fi;can calculate the groove or root width based off of the stab flankmeasured length from the design Sweet Spot; can calculate the groove orroot width based off of the load flank measured length from the designSweet Spot; can create a display or report, such as a sinusoidalmathematical curve, of the groove or root width based off of the stabflank measured length from the design Sweet Spot and/or the groove orroot width based off of the load flank measured length from the designSweet Spot; can display or report the errors/variance to designparameters of each groove width location from the datum face up thetaper cone of a thread system; can calculate the length and radialcircumferential location from the design Sweet Spot to the measuredlocation; can provide a best average of any groove width and locationthat is out of design tolerance, which groove width is smaller thandesign parameters; can display or report, such as by plotting make-uplength loss based on grooves or roots that are narrower than designwidths; can measure the lead parallel to the Z-axis axis; and/or candisplay or report, such as by plotting, all stab and load flanksrelative to the datum for “Drunken” lead of each flank; and can storeall measured values to one or more files, including operators name, partserial number, job order number, date, pipe heat numbers andtraceability certifications.

Other and further embodiments utilizing one or more aspects of theinventions described above can be devised without departing from thespirit of Applicant's invention. For example, only, a given embodimentmay or may not include both wireless and wired communicationcapabilities. Further, the various methods and embodiments of themethods of manufacture and assembly of the system, as well as locationspecifications, can be included in combination with each other toproduce variations of the disclosed methods and embodiments. Discussionof singular elements can include plural elements and vice-versa.

The order of steps can occur in a variety of sequences unless otherwisespecifically limited. The various steps described herein can be combinedwith other steps, interlineated with the stated steps, and/or split intomultiple steps. Similarly, elements have been described functionally andcan be embodied as separate components or can be combined intocomponents having multiple functions.

The inventions have been described in the context of preferred and otherembodiments and not every embodiment of the invention has beendescribed. Obvious modifications and alterations to the describedembodiments are available to those of ordinary skill in the art. Thedisclosed and undisclosed embodiments are not intended to limit orrestrict the scope or applicability of the invention conceived of by theApplicants, but rather, in conformity with the patent laws, Applicantsintend to fully protect all such modifications and improvements thatcome within the scope or range of equivalent of the following claims.

What is claimed is:
 1. A screw thread inspection system, comprising: aframe comprising a first portion configured as a datum referenceconfigured to engage a thread-bearing product, and a second portion; adimension measurement system coupled to the second portion of the frameand configured to determine distance from the datum reference along afirst measurement axis defined by the frame; the dimension measurementsystem also configured to translate relative to the frame along a secondaxis perpendicular to the first axis; and a data processing systemconfigured to receive and manipulate distance data communicated to thedata processing system by the dimension measurement system.
 2. Thesystem of claim 1, wherein the second axis is a second measurement axis,and the dimension measurement system is configured to determine distancealong the second axis.
 3. The system of claim 2, wherein the dimensionmeasurement system is coupled to a trolley configured to translate alongthe second axis relative to the second frame portion.
 4. The system ofclaim 1, wherein the dimension measurement system comprises a slider, ameasurement head at one end of the slider and a thread contact probeassociated with the measurement head.
 5. The system of claim 4, whereinthe dimension measurement system comprises a support structureconfigured to augment the structural rigidity of the dimensionmeasurement system.
 6. The system of claim 1, wherein the dataprocessing system is housed with or adjacent the dimension measurementsystem.
 7. The system of claim 1, wherein the data processing system isremote from the dimension measurement system.
 8. The system of claim 7,wherein the dimension measurement system comprises wired or wirelessdata transmission capability to the remote data processing system. 9.The system of claim 8, wherein the remote data processing system isselected from the group consisting of: a smart phone, a tablet, an iPad,a laptop computer, a computer, a website, or any combination thereof.10. A method of inspecting a screw thread system with the system ofclaim 1, comprising: contacting the datum reference to a dimensionalreference associated with the thread system; zeroing the dimensionmeasurement system along the first axis to the dimensional reference;translating a contact element associated with the dimension measurementsystem along the first axis to a first thread system artifact;transmitting data to the data processing system representing thedistance along the first axis from the dimensional reference to thefirst artifact; translating the contact element along the first axis toa second thread system artifact; transmitting data to the dataprocessing system representing the distance along the first axis fromthe dimensional reference to the second artifact; and determining thedistance between the first and second artifact.
 11. A method ofinspecting a wedge thread system having a plurality of stab flanks and aplurality of load flanks with the system of claim 1, comprising:providing a wedge thread inspection system comprising a frame comprisinga first portion configured as a datum reference, and a second portion; adimension measurement system coupled to the second portion of the frameand configured to determine distance from the datum reference surfacealong a first axis defined by the frame; the dimension measurementsystem also configured to translate along a second axis perpendicular tothe first axis; and a data processing system configured to receive andmanipulate distance data received by the dimension measurement system;contacting the datum reference to a dimensional reference associatedwith the wedge thread system; zeroing the dimension measurement systemalong the first axis to the dimensional reference; translating a contactelement associated with the dimension measurement system along the firstaxis to a first thread system artifact; acquiring data representing thedistance along the first axis from the dimensional reference to thefirst artifact; translating the contact element along the first axis toa second thread system artifact; acquiring data representing thedistance along the first axis from the dimensional reference to thesecond artifact; and determining the distance between the first andsecond artifact.
 12. The method of claim 11, wherein the first threadsystem artifact is a stab flank and the second artifact is a load flank.13. The method of claim 12, further comprising: acquiring a plurality ofadditional stab flank distances along the first axis for the threadsystem; and determining a stab flank lead for the thread system.
 14. Themethod of claim 12, further comprising: acquiring a plurality ofadditional load flank distances along the first axis for the threadsystem; and determining a load flank lead for the thread system.
 15. Themethod of claim 12, further comprising: acquiring a plurality ofadditional stab flank distances along the first axis for the threadsystem; calculating a stab flank lead for the thread system; acquiring aplurality of additional load flank distances along the first axis forthe thread system; calculating a load flank lead for the thread system;comparing at least one of the calculated stab lead and load lead againsta corresponding design lead; and reporting a variance between the atleast one of the calculated stab lead and load lead and thecorresponding design lead.
 16. The method of claim 15, furthercomprising: generating a report from the measured data, which includesat least one of: an operator's name, a part serial number, a job ordernumber, a date, a pipe heat number or a traceability certification. 17.The method of claim 12, further comprising: determining whether thethread system suffers one or more drunken leads.
 18. The method of claim11, wherein the first and second artifacts are associated with apredetermined thread design sweet spot having a design distance from thedimensional reference.
 19. The method of claim 18, further comprisingcomparing at least one of the stab flank distance or the load flankdistance with the predetermined sweet spot design distance.
 20. Themethod of claim 19, further comprising creating a report of the variancebetween the at least one of the stab flank distance or the load flankdistance and the design distance for the predetermined sweet spot.